How do you store 10.8 billion tons of waste?

Preliminary plans have proposed two tailings storage facilities (TSFs). Combined, these TSFs could store 2.5 billion tons of mine waste, less than a quarter of the estimated 10.8 billion tons of ore on site. The illustration above shows the height of the tallest of several dams initially considered to impound the tailings at one of the TSF’s (Site A). This dam would measure over four miles long and 740 feet high, taller than the Hoover Dam.

The estimated 10.8 billion metric tons of waste rock associated with the Pebble mineral resource far exceeds the total proposed storage capacity of the two preliminarily described TSFs. Project developers will likely seek permits to store a small amount of waste (relative to the size of the deposit), and once operations are underway, return to seek additional permits for storage space that currently cannot be defined.